In some circumstances, a patient's body is unable to heal a wound on its own. Many factors can cause a particular wound to become a hard-to-heal wound, such as the size and severity of the wound, the patient's age, illness, the location of the wound, the nutritional intake of the patient, etc. One example of a hard-to-heal wound is an injury to a peripheral nerve. Following peripheral nerve injury, for example, surgical nerve repair (neurorrhaphy) is typically done by suture or fibrin glue, which causes the nerves to regenerate across the repair site in an exuberant manner (e.g., with regenerating axons aberrantly growing out from the repair site). Simultaneously, a classic tissue repair cascade is underway with fibroblasts laying down collagen to bind the nerve ends and any damaged surrounding tissue.
Typically, the response is excessive and profuse scarring appears within the nerve repair site and around the nerve. The excessive response creates a compressive sheath and adherence to muscle and other subcutaneous tissue, thereby preventing essential gliding of the nerve and blocking regeneration. Additionally, aberrant regenerating neurites escape the repair site. The result is compromised regeneration with fewer axons heading down the distal nerve stump, as well as a painful adherent neuroma. Revision surgery to help improve poor nerve function centers on dissecting scar off the nerve (neurolysis) to help promote better blood supply and nerve gliding. Unfortunately, the scarring response occurs again and compromises this attempt.